various devices for rescuing persons from avalanches (in the following also designated as avalanche rescue devices) are already known. Moreover, various devices are known which indicate the position of a person buried in an avalanche.
An avalanche rescue device is described for example in the German patent document P 32 37 060, and comprises a rescue backpack having two chambers, each of which contains a balloon which is filled by means of a gas-air mixture from pressurized gas containers. The inflated balloons cause the user, when he/she is swept along in an avalanche, to be subjected to a buoyant force and virtually be carried on the surface of the avalanche.
A further avalanche rescue device based on this principle is known from the Austrian patent document 366917.
Another device of this generic type is known from the European patent document EP 0 957 995, in which it is designated an avalanche air bag.
Various devices are furthermore known for indicating the position of persons in avalanches. There is, for example, a so-called avalanche ball. This is a device that the user straps on over his/her backpack. When this device is triggered, a structure separates which mechanically deploys like a Chinese lantern. An avalanche cord of an extended length is affixed to this Chinese lantern and, in turn, is connected to the user. Since this Chinese lantern will buoy upward in an avalanche's snow mass, this should enable being able to quickly visually locate a person buried in the avalanche.
What all these mechanisms and devices have in common is that they have to be released or actuated by the wearer, respectively user. This is usually done manually by the user initiating a release mechanism, for example by striking an airbag, and thus by impact actuation. In the context of the present documents, the term “release” is understood to be an actuation of an avalanche rescue device, respectively a device for indicating the position of persons in avalanches, whereby the respective device is set into a state in which it is able to exercise its rescue function or its position-indicating function.
There are essentially two problems associated with the user releasing an avalanche rescue device or a position-indicating device (this will be designated in the following as intrinsic actuation or self-release). On the one hand, the person concerned must recognize that he/she has already been caught by or is just about to be caught by an avalanche. A release must then of course take place as immediately as possible.
If the person concerned has already been caught by an avalanche and/or has already been swept down, then he/she must be capable of effecting the self-release, respectively intrinsic actuation, in the midst of the dynamics of the avalanche rushing downhill.
In practice, there have been multiple cases in which persons outfitted with an avalanche rescue device, respectively a position-indicating device, were no longer able to release the device they were wearing. Thus, numerous avalanche accidents have occurred in which the persons caught in the avalanche have lost their lives, although they were equipped with an avalanche rescue device but were no longer able to release same.